Collect the types used in is-checks in the resolver phase.

lib/compiler/implementation/compiler.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
 const bool REPORT_EXCESS_RESOLUTION = false;
@@ skipping 353 matching lines @@
 
     addForeignFunctions(jsHelperLibrary);
     addForeignFunctions(interceptorsLibrary);
 
     libraries['dart:core'] = coreLibrary;
     libraries['dart:coreimpl'] = coreImplLibrary;
 
     assertMethod = coreLibrary.find(const SourceString('assert'));
 
     initializeSpecialClasses();
-
-    //patchDartLibrary(coreLibrary, 'core');
-    //patchDartLibrary(coreImplLibrary, 'coreimpl');
   }
 
   void importCoreLibrary(LibraryElement library) {
     Uri coreUri = new Uri.fromComponents(scheme: 'dart', path: 'core');
     if (coreLibrary === null) {
       coreLibrary = scanner.loadLibrary(coreUri, null, coreUri);
     }
     scanner.importLibrary(library,
                           coreLibrary,
                           null,
@@ skipping 182 matching lines @@
     phase = PHASE_COMPILING;
     processQueue(enqueuer.codegen, main);
     log("Recompiling ${enqueuer.codegen.recompilationCandidates.length} "
         "methods...");
     phase = PHASE_RECOMPILING;
     processRecompilationQueue(enqueuer.codegen);
     log('Compiled ${codegenWorld.generatedCode.length} methods.');
 
     if (compilationFailed) return;
 
+    // TODO(karlklose): also take the instantiated types into account and move
+    // this computation to before codegen.
+    enqueuer.codegen.universe.computeRequiredTypes(
+        enqueuer.resolution.universe.isChecks);
+
     backend.assembleProgram();
 
     checkQueues();
   }
 
   void processQueue(Enqueuer world, Element main) {
     backend.processNativeClasses(world, libraries.getValues());
     world.addToWorkList(main);
     progress.reset();
     world.forEach((WorkItem work) {
@@ skipping 328 matching lines @@
     final endOffset = end.charOffset + end.slowCharCount;
 
     // [begin] and [end] might be the same for the same empty token. This
     // happens for instance when scanning '$$'.
     assert(endOffset >= beginOffset);
     return f(beginOffset, endOffset);
   }
 
   String toString() => 'SourceSpan($uri, $begin, $end)';
 }